South Korean Foreign Minister Ban Ki Moon said Thursday that intelligence indicating a possible launch of a North Korean ballistic missile is "very much alarming" and that it could set back diplomatic efforts to resolve the crisis over Pyongyang's nuclear ambitions.

"We have gotten that intelligence report that North Korea appears to be preparing to launch a missile," Ban said in an interview. "We are very concerned about the North Korea activities. We hope that they will not launch this kind of missile at this time."

Ban said a missile launch would have an "immensely negative adverse impact on the ongoing six-party dialogue process," referring to the six-nation talks over North Korea's nuclear program, "as well as the ongoing South-North relationship. And I think their relationship with Japan will be very much affected in a negative way."

Secretary of State Colin L. Powell, attending meetings on the sidelines of the U.N. General Assembly, told reporters that "it would be very unfortunate if the North Koreans were to do something like this and break out of the moratorium that they have been following for a number of years." But Powell said a missile launch would not "change our approach to dealing with the North Korean nuclear problem."

Ban said he did not understand why North Korea would appear to be scheduling a missile launch, except to alarm countries in the region and gain "an upper hand" in the nuclear talks. A fourth round of talks was set for this month, but North Korea has balked at attending.

A U.S. military officer who monitors Asia said the missile in question is believed to be a new intermediate-range model detected in North Korea in the past year. U.S. analysts have said the land-launched missile is derived from the Soviet SS-N-6, a 1960s-era submarine-launched model. Some reports estimate its range at more than 3,500 kilometers -- enough to reach Guam, a U.S. territory with a large military presence.

Adding to the tension, North Korea's state-run Rodong Sinmun newspaper declared Thursday: "If the United States ignites a nuclear war, the U.S. military base in Japan would serve as a detonating fuse to turn Japan into a nuclear sea of fire."

In 1998, North Korea test-fired a ballistic missile over Japan into the Pacific Ocean. After receiving the new intelligence, Japan was reported to have sent two destroyers and a surveillance aircraft to the Sea of Japan to monitor North Korea's activities.

Ban said South Korea is "very much frustrated" that another round of talks appears unlikely soon. He said he recently told his North Korean counterpart that "they should not wait for the U.S. presidential election -- that whoever will be elected, Republican or Democrat, there will be no fundamental changes in addressing the issue."

Democratic candidate John F. Kerry has said he would allow direct talks with North Korea, but Ban noted that such talks have already taken place during the six-nation discussions, so he does not know whether there is "any substantial difference."

Staff writer Bradley Graham contributed to this report.